In the pre-recorded optical disc industry, there exists a need to uniquely identify each replicated disc. For example, a unique characteristic or set of unique characteristics for each replicated disc can be used for disc authentication, anti-piracy, and/or anti-counterfeiting purposes. Traditionally, the data on each manufactured disc remains inherently identical to other discs for the same content because each disc is a molded replica from the same master or stamper. Present methods for uniquely fingerprinting individual discs have involved physically marking or damaging the disc by laser or other means. Other methods include measuring the angular orientation of layers randomly placed on the optical disc during manufacturing. Alternatively, unique disc identification can occur by determining locations of randomly created manufacturing defects and using the created or determined information to uniquely identify each disc. However, these methods rely on a very limited amount of unique information for authentication purposes and their effectiveness can be significantly reduced if the underlying principles of the methods become known.
Thus a need exists for an improved disc identification technique that overcomes the disadvantages of the prior art.